1. Field of the Invention
My invention relates to fluid valves and more particularly relates to a needle valve of the shuttle type. The principle of the invention is a movable needle and associated piston which permit fluid flow selectively from either of the two opposite arms of a `T` shaped body. This valve is useful in breathing apparatus where it is desired to supply a patient with measured medication in aerosol or vapor form along with air or oxygen.
2. The Prior Art
The prior art includes U.S. Pat. No. 2,445,505, to Ashton and U.S. Pat. No. 3,049,148 to Richardson. Both of these patents disclose two position shuttle valves. Valves of this type are designed to operate on a differential pressure basis.
In the field of respiratory medicine intermittent positive pressure breathing apparatus has been designed to deliver medication to a patient. A device called a nebulizer is available to deliver medication without interferring with the patient's natural pattern of breathing. However, the nebulizers of the prior art require the patient to manually actuate the medication source in synchronism with the patient's breathing. The medicine cannot be supplied on a continuous basis because it would be lost into the room when the patient was not inhaling from the apparatus. This would mean that there would be no control or record of the quantity of medication received by the patient. Also, valuable medication would be wasted. In particular, the prior art requires this to be a thumb actuated switch to control the dispensing of medication. The disadvantage of this system is that it does not work with patients who have their arms or hands immobilized or patients with poor coordination or other difficulties.